Compact transmission comprising a planetary gear set

ABSTRACT

A transmission has a housing and two input/output shafts. Inside the housing is a planetary gear set with three rotatable members which are connected to the housing and the two input/output shafts. Inside the housing is a clutch which can connect two out of three of the rotatable members. When the clutch is closed the input/output shafts are connected together one to one. The pressure plate of the clutch is connected to a brake disc of a brake system that is connected to one of the rotatable members. When the brake system is closed the input/output shafts are connected via the planetary gear set. The transmission further includes a lever which can move the brake disc in axial direction and can thus open the clutch during operation.

FIELD OF THE INVENTION

The invention relates to a transmission comprising a first input/outputshaft, a second input/output shaft, a planetary gear set comprisingthree rotatable members of which a first rotatable member is connectedto the first input/output shaft and a second rotatable member isconnected to the second input/output shaft, which transmission furtherincludes a clutch having a first clutch portion which is connected toone of the rotatable members, a second clutch portion which is connectedto another one of the rotatable members and is axially movable relativeto the first clutch portion, and an axially movable pressure plate, andwhich transmission includes a brake with a brake disc that is fixedlyattached to the pressure plate and at least one brake pad fixedlyconnected to the firm object in the direction of rotation of the brakedisc and movably connected to the firm object in axial direction of thebrake disc, the brake disc being movably connected in axial direction toa third one of the rotatable members and being fixedly connected in thedirection of rotation to a third one of the rotatable members.

STATE OF THE ART

A transmission of this type is known from FR-A-1.134.821. This knowntransmission has a gear reduction between the two input/output shaftsdetermined by the indirect couplingS if the brake is closed and a directcoupling between the two input/output shafts if the clutch is closed.When the brake is closed the clutch is opened at the same time, so thatthe two can never be closed together. The known transmission takes uprelatively much space. In addition, with the known transmission it isimpossible to switch during operation because then the transmissionutilizes two gears and is consequently blocked.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a transmission of the typeset out in the opening paragraph which is more compact than the knowntransmission. For this purpose the transmission according to theinvention is characterised in that the transmission includes a housingin which the planetary gear set and the clutch are arranged while thethird rotatable member is attached to the housing. As a result, acompact construction is obtained. Since the housing can be sealed in asimple manner by means of sealing rings between the input/output shaftsand the housing, the planetary gear set can be lubricated in a simplemanner and/or the clutch can be arranged as a wet plate clutch. Inaddition, the oil baths of various mutually coupled transmissions can becoupled to each other in a simple manner.

An embodiment of the brake disc according to the invention ischaracterised in that the brake disc is situated at a distance from anaxial side of the housing, while a brake disc side turned away from thehousing forms a braking surface that cooperates with the brake pad andthe other axial side of the housing forms a further braking surface, andthe brake includes a further brake pad that cooperates with the furtherbraking surface. In consequence, a robust construction of the brake isobtained that requires little additional space.

A further embodiment of the brake disc according to the invention ischaracterised in that the transmission comprises disengaging means whichare capable of axially displacing the brake disc and thus pushing awaythe pressure plate of the clutch portions and opening up the clutch. Asa result, the transmission can also be transited to a state where thetwo input/output shafts are disengaged.

Yet a further embodiment of the brake disc according to the invention ischaracterised in that the disengaging means comprise a lever that isrotatable around a pivot which is bearing-mounted on the housing, oneend of which lever can be operated and the other end is bearing-mountedon the brake disc. As a result of this construction the two input/outputshafts can be disengaged even during operation.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description relating to the appended drawings, the wholegiven by way of non-limiting example of the transmission according tothe invention, will provide better understanding of how the inventioncan be realised, in which:

FIG. 1 shows a first embodiment of the transmission according to theinvention;

FIG. 2 shows a second embodiment of the transmission according to theinvention; and

FIG. 3 shows a third embodiment of the transmission according to theinvention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional view of a first embodiment of the transmissionaccording to the invention. The transmission 1 comprises a housing 3 andtwo input/output shafts 5, 7, while in a bore in the first end of thefirst input/output shaft 5 is arranged a shaft head-end attached to theend of the second input/output shaft 7. Inside the housing 3 there islocated a planetary gear set 9 having three rotatable members which areformed by a sun gear 11, a planet gear support 13 with planet gears 14thereon, and an annulus gear 15. The sun gear 11 is connected to thefirst input/output shaft 5, the planet gear support 13 is connected tothe second input/output shaft 7, and the annulus gear 15 is rigidlyconnected to the housing 3.

The housing further accommodates a clutch 17 of which a first clutchportion 19 is connected by means of the housing 3 to the annulus gear15, and a second clutch portion 21 is connected by means of the secondinput/output shaft 7 to the planet gear support 13. The first clutchportion 19 is constituted by a wheel attached to the housing and afurther wheel axially movable relative to the housing and fixed to thehousing in the direction of rotation. The second clutch portion 21 isconstituted by two clutch discs which are axially movable relative tothe second input/output shaft and are fixedly attached to the secondinput/output shaft 7 in the direction of rotation. One of the clutchdiscs is present between the two wheels of the first clutch portion 19and the other clutch disc is present between the movable disc and anaxially movable pressure plate 23 of the clutch. This pressure plate 23is pressed down by springs 25 and presses the clutch plates and wheelstogether.

The transmission 1 further includes a brake 27 with a brake disc 29 andtwo brake pads 31 and 33 connected to the firm object. The brake disc 29is present at a distance beside an axial side of the housing 3 andfixedly fitted to the pressure plate 23 by means of rods 35. The brakepads 31, 33 can be pushed against a side 39 of the brake disc 29 and aside 41 of the housing 3 by means of a hydraulic cylinder 37. Thesesides 39 and 41 then constitute braking surfaces. The brake disc ismovable in axial direction and is fixedly fitted to the annulus gear 15in the direction of rotation.

The transmission 1 further includes disengaging means 43 which arecapable of moving the brake disc 29 in axial direction and thus pushingaway the pressure plate 23 of the clutch means 19 and 21 and opening upthe clutch 17. These disengaging means 43 have a lever 45 which canrotate around a pivot 47 which is bearing-mounted on the housing 3. Thefree end 49 of the lever can be operated and the other end 51 isbearing-mounted on the brake disc 29. The lever 45 does not rotaterelative to the firm object and can thus be operated in a simple mannerduring functioning while this lever, via the brake plate 29, pushes thepressure plate 23 away from the two clutch portions 19 and 21 againstthe force of the springs 25 and thus opens up the clutch 17.

FIGS. 2 and 3 show two further embodiments of the transmission accordingto the invention, where the planetary gear set 9 is connected to thehousing 3 and to the two input/output shafts 5 and 7 in a differentmanner. In the transmission 53 shown in FIG. 2 the sun gear 11 is fittedto the housing 3, the planet gear support 13 is connected to the firstinput/output shaft 5 and the annulus gear 15 is connected to the secondinput/output shaft 7. In the transmission 55 shown in FIG. 3 the sungear 11 is fitted to the first input/output shaft 5, the planet gearsupport 13 is fitted to the housing and the annulus gear 15 is connectedto the second input/output shaft 7.

Albeit the invention has been described in the foregoing with referenceto the drawings, it should be pointed out that the invention is not byany manner or means restricted to the embodiment shown in the drawings.The invention also extends over any embodiment deviating from theembodiment shown in the drawing Figures within the spirit and scopedefined by the claims. For example, by adapting the construction thebrake pads 31 and 33 can be arranged in an electrically adjustablemanner in lieu of a hydraulically adjustable manner.

1. A transmission comprising a first input/output shaft, a secondinput/output shaft, a planetary gear set comprising three rotatablemembers of which a first rotatable member is connected to the firstinput/output shaft and a second rotatable member is connected to thesecond input/output shaft, which transmission further includes a clutchhaving a first clutch portion which is connected to one of the rotatablemembers, a second clutch portion which is connected to another one ofthe rotatable members and is axially movable relative to the firstclutch portion, and an axially movable pressure plate, and whichtransmission includes a brake with a brake disc that is fixedly attachedto the pressure plate and at least one brake pad fixedly connected tothe firm object in the direction of rotation of the brake disc andmovably connected to the firm object in axial direction of the brakedisc, the brake disc being movably connected in axial direction to athird one of the rotatable members and being fixedly connected in thedirection of rotation to a third one of the rotatable members,characterised in that the transmission includes a housing in which theplanetary gear set and the clutch are arranged while the third rotatablemember is attached to the housing.
 2. A transmission as claimed in claim1, wherein the brake disc is situated at a distance from an axial sideof the housing, while a brake disc side turned away from the housingforms a braking surface that cooperates with the brake pad and the otheraxial side of the housing forms a further braking surface, and the brakecomprises a further brake pad that cooperates with the further brakingsurface.
 3. A transmission as claimed in claim 1, wherein thetransmission comprises disengaging means which are capable of axiallydisplacing the brake disc and thus pushing away the pressure plate ofthe clutch portions and opening up the clutch.
 4. A transmission asclaimed in claim 3, wherein the disengaging means comprise a lever thatis rotatable around a pivot which is bearing-mounted on the housing, oneend of which lever can be operated and the other end is bearing-mountedon the brake disc.
 5. A transmission comprising: a first input/outputshaft; a second input/output shaft; a planetary gear set comprisingthree rotatable members, including a first rotatable member connected tothe first input/output shaft, and a second rotatable member connected tothe second input/output shaft; a clutch having a first clutch portionwhich is connected to one of the rotatable members, a second clutchportion which is connected to another one of the rotatable members andis axially movable relative to the first clutch portion, and an axiallymovable pressure plate; a brake with a brake disc that is fixedlyattached to the pressure plate and at least one brake pad fixedlyconnected to the firm object in the direction of rotation of the brakedisc and movably connected to the firm object in axial direction of thebrake disc, the brake disc being movably connected in axial direction toa third one of the rotatable members and being fixedly connected in thedirection of rotation to a third one of the rotatable members; and ahousing in which the planetary gear set and the clutch are arrangedwhile the third rotatable member is attached to the housing.
 6. Atransmission comprising: a first input/output shaft; a secondinput/output shaft; a planetary gear set comprising three rotatablemembers, including a first rotatable member connected to the firstinput/output shaft, and a second rotatable member connected to thesecond input/output shaft; a clutch having a first clutch portion whichis connected to one of the rotatable members, a second clutch portionwhich is connected to another one of the rotatable members and isaxially movable relative to the first clutch portion, and an axiallymovable pressure plate; a brake with a brake disc that is fixedlyattached to the pressure plate and at least one brake pad fixedlyconnected to the firm object in the direction of rotation of the brakedisc and movably connected to the firm object in axial direction of thebrake disc, the brake disc being movably connected in axial direction toa third one of the rotatable members and being fixedly connected in thedirection of rotation to a third one of the rotatable members; a housingin which the planetary gear set and the clutch are arranged while thethird rotatable member is attached to the housing; and wherein the brakedisc is situated at a distance from an axial side of the housing, whilea brake disc side turned away from the housing forms a braking surfacethat cooperates with the brake pad and the other axial side of thehousing forms a further braking surface, and the brake comprises afurther brake pad that cooperates with the further braking surface.